As a reminder of what each element is used for, here's a list of the inline elements and their uses:

ABBR
Abbreviations
Acronym
Marking acronyms - IE 4 & 5 and Mozilla 5 only
CITE
Marks citations
Code
An instance of computer code
Dfn
Definitions
Em
Emphasis
KBD
Keyboard input
Q
An inline quotation
Samp
Sample output
Span
Anything not covered by these other elements
Strong
Strong emphasis
Var
A variable

And here's the block elements and their uses:

ADDRESS
Used for marking up addresses
BLOCKQUOTE
Block-level quotations
DD
Definition description; can only be used inside a DL; should follow the term that it is describing
DIV
Used for making logical divisions for styling purposes
DL
Definition list - container for DT and DD
DT
Definition term - term to be defined; can only be used inside a DL
H1
Heading, level 1
H2
Heading, level 2
H3
Heading, level 3
H4
Heading, level 4
H5
Heading, level 5
H6
Heading, level 6
LI
List item; can only occur inside OL or UL
OL
Ordered list; signifies that the LI that occur inside it should be numbered
P
Paragraph
PRE
Preformatted text (i.e., text in which the spacing is preserved)

UL
Unordered list; signifies that the LI that occur inside it should not be numbered